α-Fe2O3 nanocrystal was encapsulated by a block-copolymer, hydroxylated poly(styrene-b-butadiene-styrene)(HO-SBS) to fabricate composite microspheres with α-Fe2O3 cores and HO-SBS shell. Its film fabricated on n-Si wafer acts as the insulator layer in the metal-insulator-semiconductor(MIS) structure. The capacitance-voltage(C-V) properties were measured to characterize the composite particulate films.